No, it's main purpose it's exactly rape and murder - with good ends being nice side bonus. Did you play Monster Girl Quest, I wonder? It's huge femdom game with 90% of its content consisted of MC's game over reverse rape scenes all of which are avoidable. There are couple of mandatory lovey-dovey scenes with main heroine though. Am I right in assuming that by your logic that game's main fetish is NOT femdom reverse rape but wholesome romance instead and people choose to play it exactly for that? ))
Well - I am one of them though. I can't get how people can be so blind to not see obvious - lot of efforts were spent on making all this "avoidable" rape and gore art for a reason. If that wasn't main fetish - they wouldn't bother to make so many h-scenes for bad ends at all. It requires time and money after all. They would did bad ends like in Fate/Stay Night - just short description and some generic blood splash picture instead. However they did exactly opposite - which shows what their target audience is in first place.
No, the goal is to open all gallery and see all possible scenes (and enjoy them). Like in all eroges with capturable heroines/arts starting from Doukyuusei era. Any dedicated otaku will do exactly that. And we both know it. There is no point in making content for people - just so they would skip it. Who is going to concentrate on "saving one heroine" and drop the game after that - especially with unlockable routes and true ending? It's not meant to be played like that and it's not what creators had in mind when they did it.